(a) Field
The present application relates to a transparent display device and a method of manufacturing the same.
(b) Description of the Related Art
In accordance with a recently last development of an Image display device in which CRT monitors have conventionally made up the main part, flat panel display devices such as a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), an organic light emitting diode (OLED), and the like has been developed, and image display devices which may also be even bent, such as electronic paper are introduced one after another.
Among these, the OLED is a self light-emitting device in which electrons injected from an electron injection electrode (cathode electrode) and holes injected from a hole injection electrode (anode electrode) are combined in an emitting layer to form exciton and the exciton emits light while discharging energy.
Due to the above-mentioned principle, since the OLED does not require a separate light source unlike the liquid crystal display which was conventionally used as a thin type display device, a volume and weight of the device may be reduced, and since the OLED has a response speed faster a thousand times or more as compared to the liquid crystal display, it leaves no afterimages when displaying a moving picture, and consequently, is highlighted as a next-generation display device.
In addition, in the case in which both the cathode and the anode are configured by a transparent electrode, a driving thin film transistor is formed of an optically transparent material, or an area occupied by the driving thin film transistor in a pixel configured by the driving thin film transistor and the OLED is decreased. A transparent active matrix OLED (AM-OLED) in which light is emitted to both sides of a substrate and information may be displayed on both surfaces of the substrate may also be manufactured.
However, in the case in which the transparent display device is implemented using the transparent AM-OLED, since the transparent AM-OLED is configured to always transmit external light, there is a problem that a black mode in which the transmitted light should be perfectly blocked may not be represented
In addition, there is also a problem that visibility is sharply degraded in outdoors in which there is a large amount of light, due to reflection of external light.
In order to solve the above-mentioned problems, display devices in which a plurality of panels performing different functions are stacked are recently highlighted, and among the display devices in which the plurality of panels are stacked, a display device in which a reflective panel selectively reflecting the external light using a liquid crystal and a display panel displaying an image are stacked has been disclosed.
However, since the above-mentioned display device according to the related art has a structure in which the plurality of panels are vertically stacked, a thickness thereof is thick, and consequently, there is a limit in implementing a transparent flexible display device.
The above information disclosed in this Background section is only for enhancement of understanding of the background and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.